The proposal addresses the need for a rapid, automated, quantitative, direct heparin assay for anticoagulation monitoring. Array Medical proposes to develop a direct, highly specific assay for heparin concentration in small (.25 ml - .5 ml) whole blood samples with a time to result of less than 5 minutes and a dynamic range of 0.5 U/ml - 7U/ml. In the proposed approach heparin is separated from a whole blood sample using solid phase matrices which selectively bind heparin. After plasma proteins and other interfering substances are washed away, using today's carbohydrate chemistry, the heparin (often being eluted from the solid phase matrix, if needed) is marked by a dye with high disaccharide affinity. The heparin concentration is determined by detecting absorbance changes at key red wavelengths after application of this dye. The absorbance is linearly correlated with the heparin concentration, providing a direct, rapid, highly specific assay for heparin well-suited to automation. In Phase I. Array will demonstrate the heparin assay and characterize its range of sensitivity in an Alpha prototype system. In Phase II. Array will improve techniques and components of the system thus increasing the speed, accuracy, and automatability of the assay. Array will construct several Beta prototype which will be used for pre-clinical and clinical studies. PROPOSED COMMERCIAL APPLICATION: This proposed project has clear and important commercial potential in critical care therapeutic monitoring of heparin in coronary artery bypass surgery, cardiac catheterization angioplasty, and in stepdown cardiac care, intensive care, and general wards where heparin is used. The worldwide market for a product of this type is estimated to be at least $50 million and as much as $1 billion.